The present invention relates to a mechanically steerable modular planar patch array antenna operable at the Inmarsat frequencies for mechanically tracking communication satellites. The antenna consists of a plurality of modules facilitating easy maintenance and repair thereof.
Conventionally, antennas are steered either electronically or mechanically. However, electronically steered antennas suffer from deficiencies in regard to the ability to track communication satellites over a broad hemispherical range. In particular, electronically steerable antennas suffer loss of communication due to gaps, holes or related RF field of view problems due to electronic scanning losses. On the other hand, use of mechanically steered antennas has been limited to use in radar systems such as that which is disclosed in U.S. Pat. No. 5,153,485. Accordingly, in the communication satellite field there is a significant deficiency in regard to the ability to effectively track communication satellites over the entire upper hemisphere.
Another deficiency associated with present radar design concerns the maintainability of the antenna, and particularly mechanically steered antennas. Mechanically steered antennas require a positioner for mechanically rotating the antenna array and for supplying the necessary electrical signal thereto. For example, conventionally positioners include azimuth and elevation drive trains including azimuth and elevation drive motors for rotating the antenna array, a rotary joint for supplying the electrical signals to the array and the elevation drive motor and the like. From the viewpoint of maintainability, it is important that the different elements of the positioner be capable of being replaced quickly and easily to minimize the down-time of the antenna. However, in conventional mechanically steerable antennas used for radar systems the positioner is built as a single unit. Therefore, when one of the components of the unit such as the azimuth drive motor is defective, an excessive amount of time is required to replace the components.
Based on the foregoing, there is a demand for mechanically steerable antennas in the area of communication systems to improve the range at which satellite signals can be received. Additionally, there is a demand for an improved positioner design which comprises various individual modules to enable replacement of specific malfunctioning modules without having to remove or replace other functioning modules.